PIPE WELDING Welding pipe is like welding any other structural shape and welding can take place in any of the normal positions for welding. When welding pipe anges and some oints con!gurations the weld applied applied may "e a !llet weld. When When welding pipe to pipe the oint is similar to a #ee groo#e and is often open root. Welding pipe to pipe re$uires a higher degree of skill and is the topic of this supplement. %he pipe welding positions co#ered are the &G at and rolled position' the (G hori)ontal position' the *G #ertical position and the +G !,ed position as shown "elow.
PIPE WELDING EDGE P-EPE-%I/N %he pipe coupons for welding are cut using the pipe "e#eling machine. %he slag is remo#ed and the edges are ground smooth for welding a &01 landing or at is applied to the pipe. %he pictures "elow show the pipe "e#eling machine and the edge preparation.
PIPE 22E34L5 %he pipe is assem"led for welding "y placing one piece on top of the other with a &01 electrode without u, on it "etween the pipe.
It is e,tremely important to set up and tack weld the pipe properly' if the pipe is not aligned on the inside it is di6cult to o"tain the proper penetration through the pipe. %he root gap around the pipe must "e consistent. If part of the root gap is too wide the key hole will open up too much while welding and instead of penetration you may ha#e "urn through 7more than &01 reinforcement8 on the inside. If part of the root gap is too narrow you may not "e a"le to penetrate through the pipe in those areas. t least 9 tack welds should "e placed around the pipe at &( o:clock + o:clock ; o:clock and < o:clock. %he tacks must "e strong enough to hold alignment while welding the root pass and should penetrate enough to "ecome a part of the root pass. When testing the tack may "e remo#ed using a cutting wheel to get a consistent root weld around the oint. %he picture "elow shows the tacks in a at position pipe.
=hill ring >or some applications a chill ring may "e used instead of an open root. %he chill ring works like a "acking "ar in groo#e welding and "ecomes a part of the welded oint. When the chill ring is used the root opening is determined "y the pins on the chill ring. fter tacking the chill ring on the inside of the pipe' the pins are remo#ed. If a chill ring is used the root pass may "e made using E?@A&1 since it is not necessary to penetrate through the pipe.
PIPE WELDING IN %BE >L% &G P/2I%I/N Pipe Welding in the at position re$uires that the Welder make some adustments to the normal angles and length of the welds during welding. In the at position with the pipe "eing rolled or rotated the push tra#el angle works "est. 2horter lengths of weld are used so that you do not change your tra#el angle "y stretching out of position. %he pipe is then rotated "efore continuing. 2tringer "eads are used to weld the root' !ll passes and co#er pass on si, inch schedule 1A pipe.
%echni$ue for welding the & G -olled Pipe %he root pass is made using the E?+A&A Electrode to penetrate through the open root pipe. 3ake sure the amperage 7heat8 is set correctly to open and maintain the keyhole where the root is s good !t. Cse scrap metal and weld in the at position with the amperage on appro,imately &AA and adust the heat as necessary. %he root pass should "e at to con#e, in appearance on the groo#e side of the pipe with no holes and should "e ush to &01 ma,imum reinforcement on the inside of the pipe.
fter completing the root pass and e#aluating the penetration' grind the groo#e side of the weld in preparation for the !ll passes. 2et the amperage for the E?@A&1 &01 Electrode at appro,imately &(A?&*A amps to weld the !ll passes and the co#er passes. Cse the stringer "ead techni$ue for welding the !ll passes and co#er passes.
PIPE WELDING IN %BE (G B/-I/N%L P/2I%I/N When welding in the (g pipe position the pipe is #ertical and the weld is hori)ontal. %he pipe is not mo#ed during welding and the welder must mo#e around the !,ed position pipe. %he preparation and amperage setting should "e the same as for the at position pipe with E?+A&A Electrodes used for the root and E?@A&1 Electrodes used for the !ll and co#er passes. It is important to layer the !ll passes and co#er passes from the "ottom pipe up to the top pipe' while keeping the weld "eads straight and properly o#erlapped.
PIPE WELDING IN %BE E-%I=L *G P/2I%I/N In the *G pipe position the pipe is hori)ontal and the weld a,is is #ertical so that the welding is essentially a #ertical weld. When welding some pipes for low pressure applications or small diameter pipe it may "e accepta"le to weld #ertical downward with an electrodes like the E+A&A howe#erF most pipes are welded #ertical upward with an E?+A&A root pass and E?@A&1 !ll and cap. When welding in the *G pipe position the weld "eads may "e either stringers or wea#es depending on the o" re$uirements. t the Delta 2chool /f %rades we use the E?+A&A electrode for the open root pass and E?@A&1 for the !ll and co#er passes using the #ertical upward wea#e techni$ue.
%E=BNICE >/- E-%I=L *G PIPE WELDING 2 always make sure the correct amperage is set for tacking the pieces and the root pass using E?+A&A electrodes. =heck the machine setting and use an amperage from
E-%I=L CPW-D WEE2 >/- *G PIPE 2tringer Wea#es may also "e used to weld the !ll passes and co#er passes. %his is an important techni$ue to learn in preparation for welding in the +G position
PIPE WELDING IN %BE +G >IHED P/2I%I/N In the +G Pipe welding position the pipe is set on a 9* degree inclined angle. %he weld in this position co#ers all position welding "ecause the "ottom of the pipe is an o#erhead weldF the top of the pipe is a at weld and the front and "ack sides are a #ertical upward weld. %he pipe is welded using stringer "eads e,cept that a slight wea#e motion must "e used to pre#ent the sides or #ertical upward part from sagging and lumping up in the middle of the weld "ead.
%he Electrode angle should remain the same for all passes. Cse a slight push angle from "ottom to top.
=-I%I=L ELE3EN%2 >/- WELDING %BE +G >IHED PIPE s for all pipe welding take the time to set up the pipe p roperly with a consistent root gap and 9 e#enly spaced tacks. 3ake sure you ha#e set the correct amperage for the electrode type and si)e as mentioned earlier. fter running the root' grind the root pass lightly "efore starting with the E?@A&1 Electrode. -emem"er to use a slight wea#e motion with the E?@A&1 to pre#ent the weld lumping in the middle and to get proper fusion. Each !ller pass should o#erlap the prior pass without lea#ing a depression 7called wagon tracks8 and should show good fusion.
%he +G pipe position is the one used e,tensi#ely for testing' since it $uali!es the welder for all position welding of pipe' groo#es' and !llets. When testingF it is ad#isa"le to remo#e the tacks instead of weld o#er them to ensure penetration at the root. wire wheel "rush and grinder may "e used to keep each pass clean and pre#ent slag inclusions. lthough there are many =odes and 2tandards that go#ern the welding and testing of Pipe' the one most widely used and recommended at the school is the W2 D&.& 2tructural Welding =ode. %he test for 23W is usually a + inch schedule 1A pipe with an open root' and is welded in the +G position. %his test $uali!es the welder for welding !llets groo#es and pipe in all positions. lso $uali!es the welder for pipe si)es from 9 inches to unlimited and wall thickness from ;0&+ inch to unlimited. n optional 23W test on 9 inch schedule 9A pipe in the +G position $uali!es the welder for all positions welding and pipe si)es from ;09 to 9 inch with wall
thickness from &01 to ;09. %he pipe si)e recommended for G%W =erti!cation is the 9 inch sch 9A pipe.
